docs: def check_feature(self, feature, readwrite):
          """Check if the *feature* is supported in the handler and
          raise an exception otherwise.
  
          **Parameters**
          
          feature: str
              Identifier for a certain feature.
          readwrite: "read" or "write"
              Check if the feature is available for reading or writing.
          
          """
  
          if readwrite == "read":
              features = self.can_read
          if readwrite == "write":
              features = self.can_write
              
          if feature not in features:
              matches = difflib.get_close_matches(feature, features)
              raise FeatureNotAvailable("Feature %s not present in %s. Close matches: %s"
                                        % (feature, str(type(self).__name__),
                                           str(matches)))